Introduction
In this challenge you will be solving date shift ciphers. Here is a general overview of what a date shift cipher is. To encode a message, you first must make a key. A key in a date shift ...

Introduction
In this challenge you will be solving diagonal Burrows-Wheeler transforms. Here is a general overview of what a diagonal Burrows-Wheeler transform is. To encode a message, you first must ...

I have created a simple encryption algorithm. Your challenge, if you choose to accept it, is to re-produce the algorithm that encodes one string into it's encoded counterpart and then back again by ...

Write a program that takes two lines of input and uses the first as a key phrase to encrypt the second according to the Playfair encryption technique.
Wikipedia describes Playfair encryption in some ...

Your task is to build a function in any language that takes a message m, an encryption e, and a modulus k (all positive integers), and takes m to the power of e modulo k. Your solution must not be a ...

I wanted to make a challenge to do the full DES encryption algorithm, but that may be a bit too involved to get a ton of participation. This challenge is to simply generate the 16 48-bit subkeys used ...

Now is the time to show off your abilities to write bad code. I am trying out a new sort of programming puzzle, most similar, I think, to the underhanded C contest. The main difference is that this is ...

You are given an encrypted string, encrypted using a very simple substitution cipher.
Problem
You do not know what the cipher is but you do know the ciphertext is English and that the most frequent ...